Note: Question is incomplete i have added the full question in picture format with answers.
Answer:
Firstly, Sweat
Secondly, NK cells
Thirdly, B-lymphocytes and T-lymphocytes
Step-by-step explanation:
Firstly, Sweat have two components, salt and water, which block bacterial, viral penetration into the body by immobilizing them.
Secondly, Natural Killer cells (NK cells) are white blood cells that attack any substance that enter into the body.
Thirdly, when infection occur B-lymphocytes make antibodies and memory cells while T-lymphocytes kill those substances with which B-lymphocytes antibody is attached.
Reference: Aristizábal B, González Á. Innate immune system. In: Anaya JM, Shoenfeld Y, Rojas-Villarraga A, et al., editors. Autoimmunity: From Bench to Bedside [Internet]. Bogota (Colombia): El Rosario University Press; 2013 Jul 18. Chapter 2.